1. Field of the Invention
The present invention relates to an endoscope apparatus provided with an insertion section to be inserted into a space to be inspected and a fluorescent member for emitting illumination light obtained by mixing excitation light and fluorescent light into the space to be inspected from a tip end of the insertion section.
2. Description of the Related Art
As well known, the endoscope apparatus is widely used in the medical and industrial fields. The endoscope apparatus used in the medical field is capable of observation of organs in a body cavity and various treatments using a treatment instrument inserted into an insertion channel of the treatment instrument as necessary by inserting an elongated insertion section of the endoscope into the body cavity to be the space to be inspected.
Also, the endoscope apparatus used in the industrial field is capable of observation of scratches, corrosion and the like and various treatments of a porion to be inspected by inserting the elongated insertion section of the endoscope into a jet engine, a piping in a plant and the like to be the space to be inspected.
The endoscope apparatus generally comprises an endoscope containing an image capturing unit disposed at the tip end including an image pickup device such as an image capturing lens, CCD and the like disposed and an elongated insertion section in which an illumination light irradiation unit provided with a light guide and the like for illuminating inside the space to be inspected from the tip end and a device body to which the endoscope is connected.
Also, in the device body, various members for driving the endoscope, specifically, electric parts such as an image processing unit for driving the image capturing unit and processing an image signal of a subject outputted from the image capturing unit, a light source for irradiating the illumination light and the like are disposed.
Here, as the light source of the endoscope apparatus, lamps with relatively large power consumption such as a halogen lamp, xenon lamp, metal halide lamp and the like are generally employed to illuminate the inside of the space to be inspected brightly, but recently, in order to reduce power consumption, endoscope apparatuses employing a semiconductor light-emitting device with low power consumption such as light emitting diode (LED), laser diode (LD) and the like as the light source are well known as disclosed in Japanese Unexamined Patent Application Publication No. 2005-205195, for example.
In the endoscope apparatus disclosed in Japanese Unexamined Patent Application Publication No. 2005-205195, such a configuration is disclosed that an LD is employed for the light source, and excitation light with short wavelength emitted from the LD, blue laser light, for example, is transmitted to a fluorescent member disposed at the tip end of an insertion section through an optical fiber, which is a light guide for illumination disposed at the insertion section of the endoscope, and the blue laser light and the fluorescent light in green and red excited by the laser light are mixed in the fluorescent member so that the illumination light having been converted to white light is used to illuminate inside the space to be inspected.
Also, such a configuration is well known that an optical sensor for detecting intensity of return light, which is a part of the illumination light irradiated from the fluorescent member is provided at the tip end of the insertion section or the device body so that a failure of the LD or bending of the light guide for illumination is detected from the intensity of the return light and power supply to the LD can be controlled based on the detection result.